Will your heat keep up?

[r.man]

I am getting the kind or temps that the stove rating is made for and mine isn't big enough for my house. My place is older, not well insulated and still has spots that are drafty. Normally my owb keeps it a very pleasant 69 or 70 degrees but today it was 58 when I got up. I had been to it 7 hrs earlier, since I was out late and knew it would be very cold, but it won't keep up with this temp outside. I know most of the members of the forum are not conversant with Celcius but it doesn't matter today because it was -39 and at -40 Celcius and Fahrenheit match. I felt better when I talked to my friend up the road who has a fairly new good large owb and found out his living room was 56 F. His has trouble keeping up at these temps as well but he is heating an old barn of a place and didn't load enough wood in besides. How many of you have been through -40 with your owbs or others and did they keep up to the need?

[upsnake]

Umm I don't think i would keep up in -40.

It as neg 6f here, not problems keeping up. It really doesn't get much colder than that here though.

[beenthere]

At those temps, I wouldn't expect an OWB to keep up. If it did at those temps, then it would be oversized for the more normal temps and become inefficient.

We had negative F temps the last couple days, and my indoor boiler was maxed out and just keeping up in this 40+ yr old house (but new windows). Temp inside didn't dip below 68° F at the coldest.
I go through about 1 wheelbarrow full of wood in 24 hours.
The boiler has a 9 gallon water capacity and does very well for its 30+ yr age and all baseboard hot water runs.

For those extra cold temps, maybe an indoor woodstove would add enough extra kick to bring at least one room up to temp. 

[tyb525]

Or one of the fancy edenpure heaters, we have a knock-off and it is nice for warming up one room if you need it.

[thecfarm]

I brought a big OWB,Heatmor,take a 54 inch stick.I brought it thinking that I will have a "working garage" someday. I kinda doubt that will happen now. But I kinda doubt we will see any -30 or -40,but never know either. It has happen.My white pine is keeping me nice and warm. Even If I would of brought a smaller I think it still would keep up. Maybe i would have to fill it 4-5 times,but I think it would keep me warm. I do have 85,000 BTU heat exchangers too. I have a stand alone unit in the basement and one was put into my plumtam of my hot air furnace. I can bring the temp up much quicker in the basement than I can with the Hot air furnace heat exchanger. I made the mistake of buying a just about big enough Monitor for my Mother's house. Did fine at about 14 above,but anything less I would have to go over and start a fire for her. The sales person said that will do it easy.  :  Quess I should of had him come over and start the fire for her. Did not make that mistake with the OWB.
beenthere you sound like that saleman that I was dumb enough to listen too. When it's kinda warm my furnace just don't take as much wood. I have no idea how inefficent that can be.Have to remember a OWB works with forced draft. If the water temp is at the high point the fans don't come on. I heat my hot water in the summer and it just sits there waiting for the water temp to drop to turn the fans on.

[chevytaHOE5674]

It was -22* and 25-30mph winds here the other night and my OWB kept this 100 year old farm house a comfortable 70* inside. Granted the blower on the stove was running continuously and the blower in my forced air furnace was as well. So given that I don't think mine would keep up at -40*. Thankfully we rarely get that cold as my other half would be upset if it was cold in the morning when she gets up for work...

[doctorb]

Couple of thoughts -

1.  The phrase, "keeping up", needs further description.  I presume that you mean that the water temp returning to the OWB is cool enough that the boiler can never increase the temp of the water in its jacket to the point that it will shut off (no idle period).   Have you watched the boiler and seen whether, under these extreme conditions, any increase in temperature is possible in the boiler?  Your OWB must be running constantly, without rest period, I assume.  Is the temp of the OWB slowly decreasing over hours and days?

2.  You mentioned that your neighbor doesn't load enough wood in his OWB.  I am not sure we know the optimal load point for each individual OWB.  Under these conditions, you are going to burn a lot more wood and will need to fill more often, but I am not sure that the size of the restocked wood load is that important to stove efficiency.  Placing a large amount of very, very cold fuel into the firebox may deter combustion for a while, but I don't know if that would that make a huge difference over a 24 hour period?

3.  I am no plumber, but larger diameter lines connecting to your OWB with larger flow pumps may help in these extreme conditions, as water moving quicker through your heat exchange system cools less and thus returns to the OWB with a higher temp, making it work less hard to "keep up"!

Interesting topic.  Want to hear what others think.

[stumper]

Mine has done fine with temps to abot -15 F.  When the temps are predicted to be below 0 I bump the temps to 190 from 185 to allow more heat to be transported with the same volume of water.  Temps are predicted to be 0 to -10 for the next couple of nights and as the bank I passed this afternoon said the temp then was -2 I do not think -15 to -20 is out of the question.  I'll load her heavy and let her go.

[r.man]

A bit more detail. I watch three thermometers at my house, the one on the boiler, one on a hot air vent and one for the main room itself. As long as the room stays within 2 degrees of its set I am happy but I prefer the vent air to be above 95 F when the inside blower is running. When it is very cold outside, below -25 F, the vent air needs to be 100 F or more or the house will start to cool. When it gets to be -40 my water temp will not hold unless I am at the stove every few hrs since my house takes too much out. Since I am not willing to go out to it in the middle of the night by morning I am playing catch-up. This problem with my system comes down to the fact that my firebox is too small. I normally fill the firebox for the night unless it is a warm winter night and if it a very cold night my firebox is just too small for the house it is heating.

[ely]

the temps you folks are talking is crazy, im pretty sure if it gets near that here im heading for fiji or someplace nicer.

[doctorb]

What make / model OWB do you have?

[Holmes]

For most of us our heat loss is figured for the coldest day being 0 and keeping the house 70 degrees.  When you go to 40 below it actually doubles the amount of heat required to keep your house at 70 degrees. It could be that your boiler is not large enough.

[stratford 50]

I heat 3300 sq ft, it is well insulated, the furnace is an e- classic 2300 and has heated my home and garage down to -33 F. Purchased in 2008 and am very happy with its performance.

[boilerman101]

This kind of weather will certainly prove if you have a large enough OWF or not. If your firebox is so small you run out of wood before morning, that will certainly cause heating problems and make catch up difficult. A small firebox also means a smaller heat transfer area to the water in the water jacket, so if OWF can't maintain normal operating temps, your home is simply pulling the heat out of the OWF water faster than it can put the heat back in. In either case, the furnace is too small. This is what irritates me by OWF companies claiming their furnace heats 5,000 (or whatever) square feet......At what outdoor temperatures? How do they know age or insulation value of that home? Ceiling heights? Amount of glass? I feel many of the new start up companies have over promised and now will be under delivering with some real winter temps we have not seen over the last 2 warm winters. I'm still able to get a 24 hour burn time at -27F with my Eclassic 2400 and a nice warm 73F inside. Yup a bit oversized fore my 2,300 sq ft. but I have seen no down side. If you can keep wood in your furnace and maintain within your normal OWF operating temps and your house is cold, then you don't have enough exchange to keep up with the homes btu needs. Bumping OWF water temp up to 190-195F, a larger exchanger or some additional radiant heat in cold rooms may be options. I see the National Weather Service is now forcasting cold below nomal temps for much of U.S. from Western ND down into southern OH and throughout the Northeast states for the month of February. Glad I'm not paying the oil man!

[beenthere]

No mention here if the wood was dry, or at least seasoned for a year or two. Unseasoned wood will burn but not produce much heat into the water.
But as DrB eluded to too, is it the OWB, the supply line, or the heat exchanger in the home that isn't doing the job expected.

[tyb525]

I think as it was stated, OWB's are sized based on 0F deg temps, not -40F deg. Sounds to me it just plain isn't big enough for a temperature that cold, if temps get that cold often it sounds like a bigger OWB is needed.

Of course larger/better insulated pipes to/from the house would be an improvement. And burning dry wood is too, if the OP wasn't burning dry wood.

[r.man]

The stove I had was made by a local company for about 10 yrs. They went out of business about 8 yrs ago when a sister company pulled them under. Everything that has been said is very true, if my lines lost less, my house was better insulated and if my wood had better BTUs then it would help but ultimately I cannot put enough wood in the stove at one time. I estimate that the firebox should be at least half again as large if not twice. Friends have bigger fireboxes and they load lighter in warmer weather and they load fairly heavy in this deep freeze.

[MJD]

My CB4436 keeps up no problem on our 1200sq.ft house, a few years back it was down to -20s and ended up loading it 3 times a day instead of 2. This morning it is -1 and a load lasted 13 hours. I piped my water from the owf right into the boiler in the basement (no heat exchanger) and just put a zone valve with its own thermostat in the line that feeds the house, in extreme cold I dont no if a water to water heat exchanger would keep up.

[Roger2561]

Well, yesterday we had -3F when I got out of bad at 3:30am, it was -4F when I left for work but, it was coupled with a 20+ MPH north wind bringing the windchill to -25F.  When I got out of bed this morning (same time) it was -15F with a 10MPH north breeze.  Needless to say it was a bit brisk.  I filled the firebox of my CB E-classic 1400 about 2/3's full at 5:00pm last evening and when I checked on it this morning at 5:00am there was 2 unburned logs and a beautiful bed coals just waiting for more logs.  I was able to keep my 3000sqft home at 70F all night.  This house is an 1840's vintage and 70F is nice and comfortable for me.  I'm in a short sleeved shirt typing this. 

I must add that God has been very good to me.  I have a nice home and it is nice and warm in here.  I truly feel sorry for the homeless or those who do not have enough money to pay for propane or oil. 

Now that Pres. Obama has won reelection, I feel that the carbon tax that no one talked about during the campaigns will become a reality as soon as the gun control becomes law.  If people think home heating oil, propane and coal are expensive now, hold onto your hats because it will get even more expensive.  Roger

[r.man]

In the rural area I am in I don't think we have homeless people. With these temperatures you can't, it's more of an urban thing. I have known people to live "rough" with very basic dwellings, no running water and basic heat but always with heat. We sometimes get the single man hermit type and I do know of one older woman who has shifted her living into one room of her house because of heating costs. Her mind and health is good but this is her way of dealing with an outdated furnace and high heating oil costs. She bought herself a pellet stove and shifts into the kitchen/living room area for the winter. I am about to go out to my furnace, it was warmer last night so the house held it's temperature fairly well. Woke up to 63 degrees instead of 58 from yesterday. I too am in a tee shirt, but I find above 60ish to be short sleeve time unless I am under the weather.

[thecfarm]

r.man,I know you said that OWB company went under,but what was the name of it? Just wondering,probably never heard of it. How big is your firebox? The machine shop that I brought my sawmill from made an OWB. I looked at it. It was a little while before I brought mine.I don't think they made another. This was a little before the EPA was looking hard at OWBs.

[sprucebunny]

My wood stove is keeping up with regular 5 hour feedings. It was -11F when I fed it at 4 AM.
It's a Vermont Castings Vigilant that I got at the dump.... By using a furnace blower in the opposite corner of the house from the stove and having the stove in it's own room that acts like a plenum, I'm heating two levels that add up to more than double the square feet the stove is rated for and one level has 12 foot ceiling. It's not a very well insulated house and tho there are no obvious air leaks, the air stays fresh and paint fumes dissipate easily so it's not very air tight. That's perfect.  8)

[stumper]

Well the KEE ChEE bird was flying this morning, you know the one, it is the one whos full call is KEE CHEE CHR***** its COLD.  BUt the boiler and my wife was warm and happy. 

Eclassic 2300, 1992 3200 square foot home plus heated basement.

[sam-tip]

What you could do is add external hot water capacity / storage.   I added two 75 gallon water heaters to my system.  I found them on Craigslist for $75 each.  They were new but damaged with no burners.  I have seen where people used 500 or 1000 gallon propane tanks for hot water storage.  Heat the water during the day and let the fire go out at night.  With enough hot water storage it will last all night.   The propane tanks needs to be insulated.   

[r.man]

Cfarm, I can't tell you the name for sure. There are no plates or names on the stove but I think the company sold under the name of "Outhouse "  stoves. The first ones were basically a Dahl , big firebox, smokepipe out the top, gravity draft. After a few years they started making these ones which have a narrow firebox, large water pipe grates, fan combustion air, a sloped floor at the back and smoke pipe out the back. If I were to fill my stove and then take the wood and put it in my friends Heatmor it would cover the floor and you could put three times that amount in it. My stove was made in a small town north or here called Combermere.

[r.man]

Sam, I have thought about adding a tank in the basement, my only concern is that with the extra volume my recovery time for a cold start is going to be longer. I did consider putting in a bypass valve and now that I have managed to scrounge a few electric valves I may try it. A little tricky when you think about it because the reserve tank has to draw heat when available and give heat when needed but not be attached while the furnace is labouring but able to keep up.

[SwampDonkey]

Forced air Fawcett, 125 year old farm house, 10 foot ceilings, -10 F this morning outside, 88 degrees in here. No going out in cold wind and snow. I must be in a dream. :D

[WmFritz]

Forced air Fawcett, 125 year old farm house, 10 foot ceilings, -10 F this morning outside, 88 degrees in here. No going out in cold wind and snow. I must be in a dream. :D

Holy Cow SD!!!    88° ?  You must be running round the house all day necked  :D

[beenthere]

If I were to fill my stove and then take the wood and put it in my friends Heatmor it would cover the floor and you could put three times that amount in it

So the only problem then is you need to fill it more often with wood?
Will your heat keep up then?

[beenthere]

I must be in a dream

SD
That is not a dream, that is a night mare. 

[sam-tip]

Sam, I have thought about adding a tank in the basement, my only concern is that with the extra volume my recovery time for a cold start is going to be longer. I did consider putting in a bypass valve and now that I have managed to scrounge a few electric valves I may try it. A little tricky when you think about it because the reserve tank has to draw heat when available and give heat when needed but not be attached while the furnace is labouring but able to keep up.

How about using a 10, 20, 30, or 50 plate heat exchanger to isolate the reserve.  Just use a taco pump to circulate the reserve tank through the plate heat exchanger.  If you don't want the reserve tank on just turn off the circulating pump. Or bypass the plate heat exchanger.

I turn the Taco pumps off during heating season start up.  Then turn one loop on at time.  I have three loops.  Shop, garage and house.

[JSNH]

R.Man there are a few no cost tricks to get by on those days.

I have hot water baseboards and zoned every bedroom. So during the day those rooms are cold. The living roon is kept warn during the day.
That keeps the heat where I need it when I need it.

It sounds like you have forced air find a way to block off unneeded spaces and direct the heat where you need it.

Curtians closed at night it really reduced the heat loss.

Never run the clothes dryer on a day that cold. You are just pulling in the cold air.

Cook something in the oven for dinner it adds heat to the house.

Save some of your best wood the really dense dry stuff for the -40 nights.

I am sure you are doing some of these things already with out even thinking.

Good luck keep warm.

[delgra]

r.man, I'am living in Combermere now for 40 years and I did not know stoves were made here! Can you expand on the stove a bit?
Thanks
Bob

[SwampDonkey]

I didn't consider it as a nightmare. All I felt was nice and warm. Dry heat is different than sop'n wet humid heat.

[thecfarm]

Swampdonkey you must be one of them that keeps his wood in his basement? You always like to say you never are cold feeding your stove,so you must have it in the basement or in the bedroom.  :D I had to go out in the cold to bring the wood into the house. I use to throw a little into the basement. I built about a 4 foot box around a basement window to throw wood into. That worked real good.I have 2 wood stoves in my house still. I like to go out in the cold and fill my OWB. If you never had a OWB,don't knock it until you try it. You just might like it.   ;)  I would not want the wood inside my house again. My OWB is just about the best thing I ever brought.

[petefrom bearswamp]

2005 classic 4436, 3200 sq ft house 19 yrs old.
Usually stoke 2x a day with 10 pieces.
For the last two days have been doing 15 pieces.
House temp from 72 to 73 F.
Am going to try an anecdotal study on temps at the OWB boiler jacket, into my plate exchanger out of same and inside oil boiler jacket temp.
Not scientific but will satisfy my curiosity.

[r.man]

Bob the stoves were marketed by Pine Tree stoves. The fellow that gave me the one I am using is bringing me the owners manual tomorrow. Pete what I have been wondering for years is the weight of wood going into each of these stoves. Everyone says so many pieces and then they will classify it as small, medium or big but everything is relative. I call a 100 lb a big piece of wood but not everyone does. Weight and species with outside temp and square footage would provide a lot of insight into stove efficiency. I might tackle this if I had dry wood and an easy way to weigh multiple pieces so it didn't take up much time. I think some of the retired guys out there should give this a shot to inspire the rest of us.

[r.man]

Oh and JSNH, I do all of those things and a few more on cold days. Next year I want a bigger firebox and an indoor backup that could be used to augment if it goes to -40. I have a line on an indoor wood furnace that is locally known as a good design. Interesting fact, 78 yrs ago Ontario logged its coldest recorded temp at -58.3 degrees F.

[SwampDonkey]

Takes me 3 days in the spring to store 7.5 cord away in the basement and 1.5 in the shop. Way ahead of the game. Done, no fishing for wood in the winter, no ice and snow on it and no facing that blast of cold fishing for it. Nice, warm and dry. Dry wood, so better heat value by volume. ;D I always figured if I had a serious injury and if I could at least crawl and was confined to the house I wouldn't worry about freezing to death. If it was any worst, I wouldn't worry about it either, just dig me a hole. :D

[r.man]

Swamp I am trying to reform and do my wood like that but I haven't managed it yet. One year I did have a tandem load cut, split and covered in the back yard by fall. I backslid this year, way back. The stove I have has to have small wood but every other stove I have had could take long, large blocks. I started cutting my wood reasonably small so that anyone could load it in case I got sick or hurt. I have a couple of friends that could load big wood if needed but many people can come in if the wood is normal size. I also shifted my woodpile closer to the stove this year. A bit more convenient. The farthest wood is an easy toss for a big block to land in front of the stove.

[martyinmi]

We've had around zero temps at night all week and single digits during the day. I've been filling mine about 2/3rds full(it only holds 11 cu. ft when it's totally empty) every 12 hours, give or take an hour either way. I have a two wheeled 8 cu. ft. wheel barrel that I heap as full as I can that will last me 1 and 1/2 days in this weather. We keep both stories of our house at least 72* all the time. My OWB cycles a lot, but the fact that it does cycle tells me that it still has plenty more to give should Mother Nature decide to throw more cold our way.
My place is about 1800 sq. ft. and poorly insulated.

[r.man]

Bob, I got the original owners manual for my stove today. Bought in 98, with the firebox warrantied for 10 yrs. That might have been what put them out of business. A friend gave me one of the original Dahl style stoves and I liked it but it finally became unfixable 3 yrs later. It originally was leak free for 3 yrs and then had to be repaired almost every yr after. My friend had enough after about 8 yrs and gave it to me. The one I have now is the newer style and lasted about 9 yrs before the tank developed a large leak. The company was gone by then so a different friend gave me it. It was marketed as " Outhouse Wood Stove " from " Pine Tree Wood Heat, a division of Hinterland Handcrafts Limited ". Hinterland operated in Bancroft or Birds Creek I think. Both went under at the same time.

[yellowrosefarm]

I hope I never see -40. Got down to 10 here which is plenty cold for us. I have a Shaver 250 for a small 100 year old 2 story cape cod farmhouse and a 24x32 garage. I'm filling it about every 12 hours and it has no trouble keeping the house at 72 and the garage at 60. Even cycled the draft fan off before I went to bed on the 10 degree night.  I don't think it would have done that last year before I put the larger 75cfm blower fan and homemade draft control on it. I would have done that right off if I had realized what a big difference it would make.

[John Mc]

Sam, I have thought about adding a tank in the basement, my only concern is that with the extra volume my recovery time for a cold start is going to be longer. I did consider putting in a bypass valve and now that I have managed to scrounge a few electric valves I may try it. A little tricky when you think about it because the reserve tank has to draw heat when available and give heat when needed but not be attached while the furnace is labouring but able to keep up.

I haven't quite thought this all the way through yet, but I'm wondering if there is a way to solve this with a mixing valve, or something similar.  The output of the valve would flow to your heat load (i.e. to your house).  The "cold" water input to the mixing valve would be your storage tank.  The hot water input would be direct from your boiler.  With the mixing valve set properly, it would pull as much water
from the storage tank as it could, mixing in enough boiler water to bring what was headed to your house up to the desired temp.

As far as heating up the storage tank, I'm sure there are controls out there that will let you set a priority -- for example "send no heat to my storage tank unless the output temp to my house heating loops are at least X˚."   I believe I've seen this on a commercial-scale wood chip boiler in a nursing home. They have very large capacity tanks for domestic hot water (showers, baths, sinks, laundry).  Their priority is heating the building.  Under most circumstances, the boiler can handle both, but when the loads get really high (very cold out, or every zone wants heat at once), they have the ability to tell the domestic hot water to "wait a minute while we heat up poor old Mabel's room before we send you any heat". 

The nursing home system was controlled by a Programmable Logic Controller (a PLC - basically a small computer), but I've got to believe someone has already solved the problem you describe with some sort of control system for residential applications.

John Mc

[woodmills1]

I have thought about an extra tank to add volume to my system, as my heat monster can get behind.  I have been using nearly a quarter of a cord a day for the last week, dry pine, standing dead ash and green ash mixed.  If I sleep too long the water temp drops and it is hard to get the water temp back as the house sucks much of the heat as the stove plays catch up

If I added an extra tank it might be enough to give me an hour or two before the temp falls too much


I would just plumb it inline with, a bypass and 4 shut off valves.
on start up close the valves to the tank and open the bypass.
once temp is reached close the bypass and open the tank

[r.man]

Woodmills, I sometimes have trouble getting my tank temp up and therefore my house temp and I have successfully used a strategy that shouldn't work but does. I turn my house fan off for an hour or so to let the tank temp rise. In the long term this should not make any difference in overall temp but it does. My house will not increase unless the tank temp is over a certain amount ( this value varies with the outside temp ) and the tank temp won't rise with the house taking away heat. Typical catch 22. If I turn the house fan off the tank gains and the house drops but the house then seems to recover faster so in the long run I am better off. I have tried for hours sometimes to raise the house temp and it just sits there, turn off the fan, wait an hour or a couple of degrees loss and then turn the fan back on. Seems to work, don't know why.

[John Mc]

r.man -

I don't know what kind of system you have, but I wonder if once the temperature drops, you are pulling too much heat out of the combustion area to get an efficient burn (a colder fire wastes a lot of BTUs as unburned gasses go up the chimney).  Maybe turning off the house fan reduces the load enough to allow combustion temperatures to get up into the normal range, and once it's burning efficiently, the system can keep up OK?

Just a thought.  It's the only thing I can think of to account for the effect you describe, especially if it's a lasting effect, and not a case of you just slowly puling the heat in the tank back down again after you start the fan.

[woodmills1]

yes that trick works fine
If I wake up late and feel a chill in the house, the first thing I do is turn off the furnace fan, and yes the stove temp recovers much quicker

I have an oversized heat exchanger in the furnace and I think my heat monster house can pull heat faster than a new fire can build water temp.  once the water temp is up the house will recover

sunshine also helps

my system is very poor in design

much of the heat I make is lost to the miles of uninsulated duct work with very few returns

If I do burn oil, nearly half of my house will not get above 60.
at least with wood, even with the less than zero of the last week, I get to 66 67

[woodmills1]

water can hold a lot of heat, and thus it takes a lot of heat to raise its temperature

Back when I taught I used to boil water in a dixie paper cup using a bunsen burner

[stumper]

Sorry, it has been a long time since my thermodynamics class but I fail to see how a tank will help a boiler keep up with cold temps.  A boiler will store heat and prolong both burn times and and the idle times.  However, the issue of will it keep up is a BTU per hour issue.  Once the heat demand exceed the available heat out put of the boiler then the boiler will not keep up, holding more BTU's in a tank will not change that.

[woodmills1]

not to help the stove keep up, but maybe help it keep from getting behind in the first place.  It would have more stored BTU's.  I don't think it would provide much of a cushion but my system has less than 200 gallons as it is.  Mine only gets behind when the wood is low.  If the stove is charged the house is warm.

when it is below zero day and night for a few days, the chance of me either sleeping to long or being away is real so the wood can burn low

my house demands heat, so about an hour after low wood the water temp is going down fast

[Holmes]

 A 500 gallon storage tank will have 4,150 lbs.of water in it. If you heat it to 180 degrees you will have  around 70 degrees of usable stored heated water. {180* to 110*}     70x 4150 =290,500 btu's of stored heat .  That stored heat will help the boiler keep up with the overwhelming heat loss. I think he would need a 1000 gallon storage tank to get thru the minus 40 weather.   I hope this helps.

[Ianab]

If you can store BTU's in a hot water tank, this means you have a reserve of heat for times of peak need.

Then the furnace need only produce the average BTU's needed over the day. During warm times the furnace still runs at a higher burn and stores heat for the coldest time of the day.

It allows a smaller furnace to actually provide more BTU's over the course of the day, even if the peak isn't any more.

Ian

[r.man]

Short term help only. Which is why an extra tank would need to be valved so that it could remain cool after giving up its stored heat. Same premise as the batteries on an off grid system. I have wondered whether a large heat mass would be better. Maybe instead of insulating immediately below a concrete slab the insulation should be 4 ft down with a set of heat pipes there to heat the gravel mixture below the floor. Harder to control, probably quite a learning curve but the same principle as a masonry heater, large mass slow release of heat.

[Holmes]

A heat sink might be a good idea if you could load it up before the cold snap arrives.

[sprucebunny]

I use the heat sink idea by heating my 6" slab in the downstairs with the radiant oil furnace before a cold snap. I can get the slab up to 75 in just a few hours. Then the warm air from the wood stove system will keep it from dropping fast or the slab will keep the whole house at a bearable temperature for a couple days at more moderate outside temps without using the wood stove at all.

[r.man]

That's what I am talking about but imagine your slab being 4 ft deep.

[stumper]

OK I get your concept.  Create a big heat storage and keep it warm until the cold hits, then drain the heat from it, isolate it till it warms up, and when warm reheat it.  Yes I can see that could help for a quick hit cold snap (one night). 

It would be of little help in my area as when we get cold snaps they last for several days. 

Now on the other hand, it could be of use in the summer time when I only heat my domestic hot water.  If it were large enough I could fire the boiler bring everything up to 190-195, let the fire go out and run off the store heat till the temp got down to stay 160 (my hot water is set at 140 and if I recall 160 was as low as I could set the heat setting on my furnace without changing out the controller).  Assuming minimal heat loss, 1000 gallons of heat storage would give me about 300 gallons of usable hot water (about 3 days with my family of 4). 

[John Mc]

Stumper -

That's exactly how systems which are designed with large storage tanks work.  I believe this set up is much more common in Europe than in the US, though we are seeing more of them with large storage tanks (some in basements, some buried underground).

The reasoning behind it is more for efficiency improvement and pollution reduction.  In general, wood boilers burn most efficiently and cleanly when they burn long and hard (at something approach the max load the boiler can handle).  A big storage tank allows you to do this, rather than having a bunch of short-duration and/or low-output fires.

A side effect is that this also allows a system to absorb short duration peak loads which may be above the boiler's rated output.  A sunny day/frigid night, or even a couple of frigid days can be "bridged" with this system.

Industry "Best Practices" for  commercial scale wood chip boilers (I'm talking 500,000 to million BTU and larger systems) do not use a single boiler designed to handle all of the peak load (at least not here in New England or in similar climates).  Typically, the boiler will be designed to handle 60-70% or so of the peak loads, with the peak being supplemented with other heating sources (sometimes even a smaller wood chip boiler).  Wood boilers do not have as good a "turn-down ratio" as oil or gas boilers.  A very well designed wood combustion system (I'm talking about computer controlled, larger scale systems here) will only turn down to about 30% output before it loses a lot of efficiency and burns rather dirty, making it unusable in the spring and fall. 

As it turns out, a system which employs wood chip boiler sized for around 65% of peak load here in the northeast, and supplements with fuel oil will actually burn LESS fuel oil than a system where the wood chip boiler is sized for 100% of peak load with a smaller oil burner for the "shoulder heating seasons" in the spring and fall.  This is because the larger system can't "turn down" well enough to burn reliably, efficiently, and cleanly enough to be used in the spring and fall.

[r.man]

I would think that cooling and heating systems are the same way since some employ two stages to achieve full load.

[stumper]

I have heard of this heat storage for solar systems, so I did a quick search.  http://www.americansolartechnics.com/index.html this site has insulated storage tanks.

[snowstorm]

if its 20 below and the wind blowing the temp in the house will drop to 67. i think its mainly because i am asking to much from the in floor heat. the house is a cedar log cabin 30x56 with 17' ceilings the garage is 40x40x15. i use a taylor t1000 it holds about 900gal of water. works well

[r.man]

Snowstorm, I wonder what it would have gone to if it had been -39 F. At -20 is your system cycling at all?

[John Mc]

if its 20 below and the wind blowing the temp in the house will drop to 67. i think its mainly because i am asking to much from the in floor heat. the house is a cedar log cabin 30x56 with 17' ceilings the garage is 40x40x15. i use a taylor t1000 it holds about 900gal of water. works well

So is your boiler running flat out, and just can't keep up, or is it doing fine but you just can't radiate enough heat into your house?

[snowstorm]

i think i am just asking to much from in floor heat. too much air space to heat . the garage with 2 modines would stay at 70 all winter if you wanted

[John Mc]

I'm not sure how airtight your house is, but my in-floor heat has no problems keeping up (on the days I'm not heating with my wood stove).  If you've got air infiltration issues (leaks around wind and door framing, or other areas), that's the first place to tackle, then adding insulation where it may be lacking.

I'm not sre wat temperature you are running for the water on your in-floor heat, but if you are not already at the upper limit of what is safe, you may want to try tweaking that up a bit by adjusting your mixing valve.  I know you've got to be careful of not trying to drive too much heat through wood floors... tile or cement can take a bit more.

[doctorb]

I strongly agree with John Mc.  Lots of variables with radiant heat, but once the material of that floor gets to temp, it should hold the room temp unless heat loss is excessive.  What temp is the floor water, and what temp is the water returned to your stove?

[beenthere]

Seems from the beginning, that r.man's problem is the burn chamber in his OWB is just too small to hold the amount of wood that will keep him in hot water all night.  It's a size problem at the OWB.
r.man doesn't want to get up in the middle of the night, and I don't blame him as he has to go outside. 

[r.man]

Most of the time in very cold weather my owb will not hold enough wood but at other times it hangs up the wood, either on the sides or the ramp or it plugs the grates with ash. Nothing like a cool house, a cool tank and wood sitting in the firebox unburnt for some reason.

[Ivan49]

Been watching this for a while. I have a WoodMaster 4400 and it keeps up fine. We have years ago had temps as low as -20 with on heating problems . I run the temp on the out door stove at 170 and we keep the house at 73. Last week we had several nights below 0 and on one night the temp was -4 or 5 with awindchill of -25. Got up in the morning and my wife says something os wrong with the wood furnace. I asked her why and she says the house is 88 degrees. I now knew why I woke up sweating. She said I looked out side and the furnace is 170 degrees. I told her to invite our friend over for a summer cook out as they keep their house 65 degrees. What had happened was the furnace blower on the gas furnace the contacts had stuck and would not shut off. Easy fix and then the furnace did not turn on again all day 

[coxy]

i have a cb that holds 400 gal of water it heats my house and my dads but whene it gets real cold my house gets a little cold dads is like going to afraca ido bump my water temp some times up to 200 but if the wheather turns it will make it boil over  i have learnd a lot of differnt things to try from reading all the post thanks for all the tip  and keep them comming  ;D

[doctorb]

Seems from the beginning, that r.man's problem is the burn chamber in his OWB is just too small to hold the amount of wood that will keep him in hot water all night.  It's a size problem at the OWB.
r.man doesn't want to get up in the middle of the night, and I don't blame him as he has to go outside. 

Maybe another way to work around the nighttime problem is to raise the temp in the house during the day by 5-10 degrees.  That way, when you drop the thermostats at night, the OWB will kick on less often as the house has to cool down before it gives the signal for more heat, and thus more wood consumed in the small firebox.  Just a thought.